Josephson Physics of Topological Superfluids

2017 Fiscal Year Final Research Report

• Project/Area Number: 26247062
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: Keio University
• Principal Investigator: Shirahama Keiya 慶應義塾大学, 理工学部(矢上), 教授 (70251486)
• Co-Investigator(Kenkyū-buntansha): 高橋 大輔 足利工業大学, 工学部, 准教授 (80415215)
• Co-Investigator(Renkei-kenkyūsha): MURAKAWA Satoshi 東京大学, 低温センター, 准教授 (90432004)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: 低温物性 / 超流動 / ヘリウム3 / トポロジカル超流動 / ジョセフソン効果

Outline of Final Research Achievements

In this project, we study topological properties of superfluid 3He by performing experiments on Josephson effect, quasiparticle transport, and collective excitations. We have attempted to fabricate novel microslit structures on Si wafers with dimensions 1x100μm by dry etching, and make a microslab structures by ultrahigh precision machining. So far we have succeeded to fabricate 2x100μm slit structures and 1μm thick disk-shape geometry with 4nm flatness. We have also prepared an apparatus to detect Josephson and quasiparticle flow using SQUID based displacement sensor, a ultrasound cell to study collective modes, and a torsional oscillator to search for chiral edge current. These devices are installed on a PrNi5 nuclear demagnetization refrigerator, which has also been prepared in this work. Some preliminary experiments have already been performed and experiments with superfluid 3He get underway.

Free Research Field

低温物理学